proton

noun

pro·​ton ˈprō-ˌtän How to pronounce proton (audio)
: an elementary particle that is identical with the nucleus of the hydrogen atom, that along with the neutron is a constituent of all other atomic nuclei, that carries a positive charge numerically equal to the charge of an electron, and that has a mass of 1.673 × 10−27 kilogram
protonic adjective

Examples of proton in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Mars has faint proton auroras of Mars, and Uranus has faint ultraviolet emissions. Jamie Carter, Forbes.com, 26 Mar. 2025 That is because, as Earth rotates, the direction of the proton beams generated for particle collisions in the powerful particle accelerator changes. Robert Lea, Space.com, 21 Feb. 2025 Further corrosion comes from the protons, which create highly acidic hot spots. science.org, 23 Jan. 2025 This process often causes the element to change into another element, since the nucleus can lose protons. Benjamin Roulston, The Conversation, 14 Mar. 2025 See All Example Sentences for proton

Word History

Etymology

Greek prōton, neuter of prōtos first — more at proto-

First Known Use

1920, in the meaning defined above

Time Traveler
The first known use of proton was in 1920

Browse Nearby Words

Cite this Entry

“Proton.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/proton. Accessed 31 Mar. 2025.

Kids Definition

proton

noun
pro·​ton ˈprō-ˌtän How to pronounce proton (audio)
: an atomic particle that occurs in the nucleus of every atom and carries a positive charge equal in size to the negative charge of an electron
protonic adjective

Medical Definition

proton

noun
pro·​ton ˈprō-ˌtän How to pronounce proton (audio)
: an elementary particle that is identical with the nucleus of the hydrogen atom, that along with neutrons is a constituent of all other atomic nuclei, that carries a positive charge numerically equal to the charge of an electron, and that has a mass of 1.673×10−24 gram
protonic adjective

More from Merriam-Webster on proton

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